1. Field of the Invention
This invention relates to an art for correctly identifying a phenomenon by catching a change of the physical quantity like the flow rate of a fluid.
2. Description of the Related Art
Hitherto, for example, a gas meter has been available as an apparatus for catching a change of the physical quantity and identifying a phenomenon. Patent document 1 describes a gas meter for identifying a working appliance in a fluid piping system having the gas meter. A gas meter 1 in the document has a flow rate measurement unit 3 being placed in a flow path 6 connected to a household gas supplying pipe for measuring the gas flow rate at given time intervals, a computation unit 4 for finding the difference value between the flow rate values output from the flow rate measurement unit 3, and a comparison and determination unit 7 for making a comparison between the difference value calculated by the computation unit 4 and a change determination value registered in a storage unit 5 and determining a change of the working state of each gas appliance, as shown in FIG. 7. The computation unit 4, the comparison and determination unit 7, and a gas shut-off valve 2 are controlled by a control circuit 8.
In the gas meter 1 described above, a change of the difference value between the instantaneous flow rates output from the flow rate measurement unit 3 is computed sequentially and a change of the working state of the gas appliance is identified according to the change amount; the registered data and the measured gas flow rate change (difference value) are compared with each other and identification of working gas appliances 13, 14, and 15 is made possible.
Patent document 1: Japanese Patent Publication No. 2006-313114A